My '09 Subaru legacy has 62,000 on it. It's been running fine all these years. recently, my temperature gauge needle is slowly rising. Not going completely into the red but just under it. No smoke or steam coming from my engine. Happened a few times last week - once after running for 15 minutes on the highway another for running for over an hour. It does not happen regularly - it's very random. Got my radiator flushed, new thermostat, checked the hoses, checked the head gasket. Anything that could cause it to overheat is fixed. I'm thinking it's something non-engine related due to non-smoking or steaming. No engine lights go on. Just temperature gauge raising just under the red. Help! Please anybody have this problem? I'll appreciate the help.
Subarus only like OEM thermostats.
Subarus only like OEM radiator caps.
It could be a clogged radiator or cooling system. Subarus typically get stop leak to prevent head gasket issues.
It could be the water pump. (Again, Subaru's like OEM water pumps)
The check engine light would typically stay off during overheating conditions. If your car is telling you it's overheating, it's very likely that it's overheating, so don't ignore it.
I had a very similar issue with my 2006 Subaru Outback 2.5i with 145k. I replaced the thermostat, head gaskets, and water pump (all OEM parts). One of my cylinder heads was cracked and I had to replace all 8 exhaust valves. It still didn't solve overheating issue.
A few months later, I tried performing a coolant flush with Iron Tite Thoro Flush and replaced the radiator with a Denso radiatior, and that solved my overheating problem.